CATALOGUE OF THE MECHANICAL ENGINEERING COLLECTION. 35 



the cylinder hot. The steam and air are not superheated after being 

 mixed in the cylinder, but the air is heated, expanded, and mixed 

 with the steam within the heated cjdinder and acts directly upon the 

 piston of the engine. It is claimed that by heating and expanding 

 the air and mixing it with the steam all at the same time a large 

 amount of air may be used without condensing the steam and Avith- 

 out losing any of the effective power resulting from the sudden 

 expansion of the air. 



The steam generated in the boiler may be used to act directly 

 upon the engine or may be first sent through the preheated cylinder 

 and mixed with air and from there proceed to the engine. 



Cat. No. 251.285 U.S.N.M. 



FIG. 12. — ERICSSOX AIK ENGINE, 1853. 



Model of John Ericsson Air Engine. U. S. Patent, No. 13348, 1855. 

 Transferred from United States Patent Office. 



The engine is single acting and consists of two cylinders open at 

 one end connected by a crank shaft, the two cranks being 180 degrees 

 apart. Each cylinder has two pistons, an inner or " supply " piston 

 and an outer or " working " piston. The rods of the former pass 

 through a stuffing box in the latter and are operated through a series 

 of levers, rollers, and cams by the crank shaft. The "working" 

 piston has two wrist pins on either side of the stuffing box and con- 

 nected through suitable levers to the crank shaft. 



Above the cylinders is a " regenerator " consisting of a box filled 

 with coiled tubing through which the cold compressed air from the 

 cylinder passes on its way to the heating coils and around which the 

 hot air, after doing its work in the cylinders, is caused to circulate. 



When the pistons of one cylinder are at the extremity of their out- 

 ward stroke, those of the other cylinder are about to start on their 

 outward stroke by the force of expansion of the hot air admitted 



